refact: changes grammar

From now on, labels can only be declared in the 1st
position of the row (they can be indented though).

Author: boriel

src/zxbc/zxblex.py

@@ -617,6 +617,8 @@ def t_ID(t):
         entry = api.global_.SYMBOL_TABLE.get_entry(t.value) if api.global_.SYMBOL_TABLE is not None else None
         if entry:
             t.type = callables.get(entry.class_, t.type)
+        elif is_label(t):
+            t.type = "LABEL"
 
     if t.type == "BIN":
         t.lexer.begin("bin")
@@ -683,7 +685,7 @@ def find_column(token):
     return column
 
 
-def is_label(token):
+def is_label(token) -> bool:
     """Return whether the token is a label (an integer number or id
     at the beginning of a line.
 
@@ -706,11 +708,23 @@ def is_label(token):
         i -= 1
 
     column = c - i
+    if column != 0:
+        return False
+
+    if token.type == "NUMBER":
+        return True
+
+    i = token.lexpos + len(token.value)
+    while i < len(input):
+        if input[i] in {"\n", ":"}:
+            return True
+
+        if input[i] not in {" ", "\t"}:
+            break
 
-    if column == 0:
-        column += 1
+        i += 1
 
-    return column == 1
+    return False
 
 
 lexer = lex.lex()

src/zxbc/zxbparser.py

@@ -1074,7 +1074,7 @@ def p_statement_call(p):
         p[0] = None
     elif len(p) == 2:
         entry = SYMBOL_TABLE.get_entry(p[1])
-        if not entry or entry.class_ in (CLASS.label, CLASS.unknown):
+        if entry is not None and entry.class_ in (CLASS.label, CLASS.unknown):
             p[0] = make_label(p[1], p.lineno(1))
         else:
             p[0] = make_sub_call(p[1], p.lineno(1), make_arg_list(None))